<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Dec 10, 2014, at 2:36 PM, David Majnemer <<a href="mailto:david.majnemer@gmail.com" class="">david.majnemer@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Can we use _cfepch instead? MSVC linker will silently truncate section names longer than 8 characters.</div></div></blockquote><div><br class=""></div>... and I was worried about the Mach-O 15 character limit :-)</div><div>works for me.</div><div>-- adrian</div><div><br class=""></div><div><blockquote type="cite" class=""><div class=""><div class="gmail_extra"><br class=""><div class="gmail_quote">On Wed, Dec 10, 2014 at 2:27 PM, Adrian Prantl <span dir="ltr" class=""><<a href="mailto:aprantl@apple.com" target="_blank" class="">aprantl@apple.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi everyone,<br class="">
<br class="">
As the first step in preparation for module debugging (see <a href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2014-November/040076.html" target="_blank" class="">http://lists.cs.uiuc.edu/pipermail/cfe-dev/2014-November/040076.html</a>) this patch turns the *.pcm files that are used to store clang modules and precompiled headers in a platform-dependent Mach-O/ELF/COFF container, so that eventually we will be able to store debug information alongside the module in the same file.<br class="">
<br class="">
This is implemented by using the standard LLVM code generation machinery. Instead of directly writing to the output file, the serialized AST blob is attached to an empty llvm::Module as a ModuleFlag. The module is passed to the backend which emits the AST blob into a special “__clang_pch" section in TargetLoweringObjectFile*.<br class="">
On the ASTReader side, any object file is transparently unwrapped and the BitstreamReader is pointed directly to the AST section.<br class="">
<br class="">
Other than the .pcm files having an extra header inside, this patch is not meant to have any user-visible effects.<br class="">
<br class="">
Known bugs: I still need to figure out how to make c-index-test link against and register the available targets (check-all passes, but the modules created by c-index-test currently are plain old .pcm files).<br class="">
Open questions: I made up the name of the new __clang_pch section and the various flags on the different platforms on the spot. I’m open to better suggestions.<br class="">
<br class="">
Let me know what you think!<br class="">
<span class="HOEnZb"><font color="#888888" class=""><br class="">
-- adrian<br class="">
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